A new facility has been developed to investigate the formation of new particles from the oxidation of volatile organic compounds emitted from vegetation. The facility consists of a biogenic emissions enclosure, an aerosol growth chamber, and the associated instrumentation. Using the facility, new particle formation events have been induced through the reaction of ozone with three different precursor gas mixtures: an α-pinene test mixture and the emissions of Holm oak (<I>Quercus ilex</I>) and loblolly pine (<I>Pinus taeda</I>). The results demonstrate the variability between species in their potential to form new aerosol products. The emissions of <I>Q. ilex</I> resulted in fewer particles than did α-pinene, although the concentration of monoterpenes was roughly equal in both experiments before the addition of ozone. Conversely, the oxidation of <I>P. taeda</I> emissions led to the formation of more particles than either of the other two gas mixtures, despite a lower initial terpenoid concentration. These variations can be attributed to differences in the speciation of the vegetative emissions with respect to the α-pinene mixture and to each other. Specifically, the presence of β-pinene and other slower-reacting monoterpenes inhibited particle formation in the <I>Q. ilex</I> experiment, while the presence of sesquiterpenes, including β-caryophyllene, in the emissions of <I>P. taeda</I> were the likely cause of the more intense particle formation events observed during that experiment.